1. Field of the Invention
The present invention relates to a fuel supply equipment which can be suitably used in supplying fuel in a fuel tank of a motor vehicle to its engine or the like. More particularly, it relates to a reservoir unit comprising a reservoir which is installed in a fuel tank to prevent the fuel pump from racing when the remaining volume of fuel in the tank has become very small and a jet pump for introducing fuel outside that reservoir into the reservoir.
2. Description of the Related Art
A conventional fuel tank for motor vehicles or the like uses a fuel supply equipment comprising a sub-tank formed in the fuel tank, a fuel pump for sucking fuel in the sub-tank, a pressure regulator for regulating the pressure of the fuel discharged from the fuel pump by allowing part of the fuel discharged by the fuel pump to escape, and a jet pump, fixed to a wall of the sub-tank, for receiving the fuel escaping from the pressure regulator, utilizing the flow velocity of the escaping fuel to generate a negative pressure and using that negative pressure to introduce the fuel outside the sub-tank into the sub-tank.
This fuel supply equipment causes the fuel in the sub-tank to be fed to the vehicle engine or the like by the fuel pump. The pressure of fuel fed to the vehicle engine or the like is kept constant by the pressure regulator. Whereas keeping the pressure constant requires letting any excess volume of fuel escape, the energy that the escaping fuel has is utilized to introduce the fuel outside the sub-tank into the sub-tank. With this fuel supply equipment, even if the fuel in the fuel tank decreases and its surface level drops, the fuel level in the sub-tank is kept high, thereby enabling the last drop of fuel in the fuel tank to be effectively used.
When the fuel outside the sub-tank is introduced into the sub-tank with the jet pump, bubbles are apt to be introduced into the sub-tank. According to the related art, a large enough capacity of the sub-tank is secured not to allow bubbles to spread throughout the inside space of the sub-tank.
It is difficult to form a sub-tank in a resin-built fuel tank, which is coming into extensive use. In view of this difficulty, instead of forming a sub-tank, a structure in which a cylindrical reservoir having a bottom is installed in the fuel tank is beginning to be adopted. In this case, the reservoir is reduced in size with a corresponding limitation on its capacity. As a result, bubbles in the fuel fed by a jet pump into the reservoir tend to spread throughout the inside of the reservoir. If bubbles pervade throughout the inside of the reservoir, various problems will arise, such as vapor locking of the fuel pump and the failure of the intended quantity of fuel to reach the engine or the like due to the presence of bubbles in the fuel.